Filter elements are used for filtering fluid flows or gaseous media. For example, they are used for filtering an air flow that is guided into a passenger compartment of a motor vehicle. For this purpose, they can be used in particular in an air-conditioning device mounted in a motor vehicle in order to clean ambient air from health-hazardous substances, odors or the like. Examples of such filters are particle filters, odor filters or combinations thereof. A further field of use of filter elements is air filters that remove suspended particles from the air that is supplied to an internal combustion engine. Generally, such air filters have a housing in which an exchangeable air filter element is provided.
U.S. Pat. No. 4,588,426 discloses an air filter with a filter housing having at its bottom several vertically arranged rods. A filter element can be pushed onto the rods and the filter housing can be closed by a cover. The cover is screw-connected by means of a wing bolt that extends to the bottom of the filter housing. The exchange of the filter element can be realized thus in a simple way because the cover can be removed by simply releasing the wing bolt and the filter element can be exchanged by hand without this requiring an additional tool. However, it is often desirable that such a simple exchange without tool is actually not made possible because it carries the risk that the filter element is exchanged by the consumer in an inappropriate way or by a using wrong filter element. This, in turn, can cause an insufficient filtering action or can cause the filter material to wear faster.
WO 00/56423 A1 discloses an air filter with two cup-shaped housing shells that are detachably connected to each other, wherein the lower one of the shells has a conical support pipe integrated therein. Onto this support pipe, a conical round filter element is pushed and subsequently the top housing shell is placed onto the lower housing shell and is screw-connected with one end of the support pipe. In this air filter the housing shells are screw-connected to each other so that a release without tool is not possible, but the screw connection can be realized by a screwdriver so that here there is also the risk of improper exchange of the filter element with the aforementioned disadvantages.